Recent illicit drug use is associated with non- compliance to prescribed regimens. In a pilot study, we found that contingent monetary reinforcement of medication compliance, with compliance measured by specialized pill caps which record date and time of bottle opening (MEMS), enhanced compliance. We propose a follow-up randomized clinical trial to evaluate an incentive-based intervention in drug-users. The intervention differs from that in the prior study in that it is longer in duration, more specifically addresses concomitant drug use, uses non-cash reinforcement and more broadly addresses barriers to compliance by providing MEMS-Feedback Therapy. The short-term application of contingencies is designed to "prime" compliance to prescribed antiretroviral medications, allow secondary reinforcers (e.g. improved well-being) to become apparent and engage patients in MEMS-Feedback Therapy. One hundred patients with recent substance use and MEMS-demonstrated non-compliance during a baseline evaluation will be randomly assigned to either: 1) Control intervention: supportive advice around self-reported compliance and advice around the use of cues or 2) Incentives combined with MEMS-Feedback Therapy (IMF group) IMF patients will be reinforced for MEMS-verified compliance on an escalating schedule with vouchers. IMF patients will review their MEMS- generated printouts with therapists. Patients are encouraged to discuss what they thought, how they felt and what they were doing around the times that doses were missed. Onsite toxicology testing and substance abuse calendar review are used to explore temporal and other relationships between MEMS-demonstrated non- compliance and substance use. Training will be for 16 weeks. Retention of effects will be studied during an additional 16-week follow-up period when patients will download MEMS data at regularly scheduled clinic visits without receiving additional counseling. The primary outcome measure will be MEMS-measured compliance. Secondary outcome measures will include measures of service utilization and cost. Important process measures will be whether IMF (cues to remember doses, changes in substance use). A secondary aim will be to evaluate the temporal concordance between use of substances and medication non-compliance.